Engineering:Container chassis

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A semi-tractor hauling a bare chassis.

A container chassis, also called intermodal chassis or skeletal trailer, is a type of semi-trailer designed to securely carry an intermodal container. Chassis are used by truckers to deliver containers between ports, railyards, container depots, and shipper facilities,[1](pp2-3) and are thus a key part of the intermodal supply chain.

Operation

The use of chassis to haul containers over-the-road is known as drayage trucking, and is a section of intermodal, which also includes rail transport of containers using well or flat cars and overseas transport in ships or barges. Like other intermodal equipment, chassis are equipped with twistlocks at each corner which allows a container (hoisted onto or off the chassis by a crane), to be locked on for secure transport or unlocked to be lifted off.[2] The length of a chassis corresponds to which container size will fit (i.e., a 40-foot-long chassis fits a 40-foot-long container), but some models are adjustable length.[3]

A port crane lifts a container from a ship to a chassis for road transport.
Twistlocks.

Semi-tractor trucks hook up to chassis via the kingpin. When disconnected from a tractor, the chassis' landing gear can be cranked down to park it.[4]

Portable generators, also called gensets, can be mounted (underslung) onto chassis. These gensets are used to power a refrigerated container.[5]

The axle group on some chassis (especially 20-foot and 53-foot units) can be slid backwards or forwards to change the weight distribution of heavy containers, allowing safe operation and compliance with weight restrictions.

An identification number is often stenciled on chassis to track each unit in a fleet. According to ISO 6346, a chassis should have the letter "Z" at the end of its reporting mark.

Chassis can be stacked to reduce parking space.

A variation is the tank container chassis, which are used for ISO tank containers. They are characteristically longer and have lower deck height then standard chassis, ideal for transporting constantly shifting payloads. These chassis can also be fitted with additional accessories including: lift kits to facilitate product discharge, hose tubes, and hi/lo kits to carry two empty tanks. They come in tandem axle, spread axle, tri-axle, and hi/lo combo configurations.

A truck hauling a bomb cart, which are used by dockworkers to shuttle containers within a port. They have side panels instead of twistlocks which allows crane operators to quickly place containers on them to hasten the unloading process.

Chassis Pools

Bare container chassis parked at an intermodal facility.

Unlike other countries where chassis are mostly owned or long-term leased by trucking companies, in the United States most chassis are currently owned by a few leasing companies (pools) which rent out the equipment to truckers.[1](p1)[6] When a trucker leaves or enters a facility with a pool chassis, an EDI record is generated at the facility gate which identifies the trucking company and the chassis pool, and this allows the pool to invoice the appropriate trucking company for chassis usage. The system is influenced by the steamship lines and by the operation of container terminals. Firstly, containers are commonly stored on chassis as a single mounted unit at rail yards and depots–such terminals are known as "wheeled" facilities. Secondly, steamship lines offer a service called ″carrier haulage″ or ″store door delivery″, whereby they arrange the drayage of a customer’s container. The steamship line hires a local trucking company and pays the pool for the chassis usage.

As a result, steamship lines formed contractual agreements with the pools which entail that when a container is on-terminal it must be on a pool specified by the steamship line.[7](p26)[8][9] This means that at wheeled facilities, containers are mounted onto chassis selected by the steamship line before the trucker arrives to pickup.[10] Some disadvantages of this system are that it can restrict truckers' choice of which chassis to use[11] and it can cause "chassis splits", which are when a container and its required chassis pool are in different locations.

Shortages

In the United States, container chassis shortages are a chronic problem, especially during peaks in container volume.[12] There are several causes of chassis shortages, but a common problem is excessive off-terminal dwell time. Off-terminal dwell time is the length of time a shipper keeps a chassis/container at their premises. Long dwell times mean less free chassis on-site at ports and rail ramps.[13][14]

An APL 20-foot container and chassis at a loading dock.

See also


References

  1. ↑ 1.0 1.1 National Academies of Sciences, Engineering, and Medicine. (2012). Guidebook for Assessing Evolving International Container Chassis Supply Models. Washington, DC: National Academies Press. doi:10.17226/22682. ISBN 978-0-309-25863-0. 
  2. ↑ Hildebrand, Michael; Noll, Gregory; Hand, William (2018). Intermodal Container Emergencies (2nd ed.). Burlington, MA: Jones & Bartlett Learning. p. 69. 
  3. ↑ Muller, Gerhardt (1989). Intermodal Freight Transportation. Eno Foundation for Transportation. p. 113. 
  4. ↑ "Containerisation International Year Book". Containerisation International Year Book (London: National Magazine Company). 1971. https://books.google.com/books?id=KKseAQAAMAAJ. Retrieved December 22, 2020. 
  5. ↑ Filina-Dawidowicz, L.; Santos, T.; Guedes Soares, C. (2016). Maritime Technology and Engineering 3. 1. Leiden, The Netherlands: CRC Press. p. 63. ISBN 978-1-138-03222-4. 
  6. ↑ "Changing U.S. Intermodal Chassis Operations". http://www.ocema.org/cpi.html. 
  7. ↑ U.S. Container Port Congestion & Related International Supply Chain Issues: Causes, Consequences & Challenges (Report). Federal Maritime Commission. July 2015. https://www.fmc.gov/wp-content/uploads/2019/04/PortForumReport_FINALwebAll.pdf. Retrieved December 29, 2020. 
  8. ↑ Mongelluzzo, Bill (June 13, 2019). "Chassis 'utility' model proposed for ports, hubs". https://www.joc.com/trucking-logistics/trucking-equipment/chassis-%E2%80%98utility%E2%80%99-model-proposed-ports-hubs_20190613.html. "'Carriers bought the chassis and gave them away for free to attract business,' Rooney said. Then, carriers went almost full circle by renting back the chassis from the equipment providers and offering them at discounted rates, once again to attract business, he said." 
  9. ↑ Ashe, Ari (May 30, 2018). "US truckers, shippers frustrated with chassis splits, shortages". https://www.joc.com/trucking-logistics/us-truckers-shippers-frustrated-chassis-splits-shortages_20180530.html. "'in Memphis, we run a TRAC pool and then we contribute to the CCM pool. If we have assets devoted to the TRAC pool for the steamship line for an agreed upon rate, that’s the asset the motor carrier needs to use.'" 
  10. ↑ Fact Finding 28: The Memphis Supply Chain Innovation Team. A Single Gray Chassis Pool Fosters Fluid Commerce and Improves Supply Chain Velocity (Report). p. 2. https://www.fmc.gov/wp-content/uploads/2019/05/MemphisSupplyChainWhitepaper.pdf. Retrieved December 29, 2020. "truckers do not have a choice on chassis provisioning when rail operators have a mounted operational procedure. Containers are available as a mounted unit; shippers and truckers must take the unit as tendered or wait in line for a flip fee to move that container onto another chassis." 
  11. ↑ "Hapag-Lloyd Chassis Program – USA Chassis Provider Summary - January Update - Chassis Program Update". https://www.hapag-lloyd.com/en/news-insights/news/2016/01/hapag-lloyd-chassis-program-usa-chassis-provider-summary-janu_45854.html. "In cases where Hapag-Lloyd is responsible for chassis usage, we will only accept usage from the above providers and pools. If these providers are not used, the trucker will be charged directly, regardless of the terms of chassis provision." 
  12. ↑ "Long tail of US chassis shortage snaps shippers". January 22, 2019. https://www.joc.com/trucking-logistics/long-tail-us-chassis-shortage-snaps-shippers_20190122.html. "The container chassis shortage ranks with the truck driver shortage as a perennial issue that returns to disrupt supply chains whenever freight demand surges." 
  13. ↑ Ozkan, Utku (October 9, 2020). "WHY THERE IS A CHASSIS SHORTAGE AT THE PORTS OF LOS ANGELES AND LONG BEACH". https://www.morethanshipping.com/why-there-is-a-chassis-shortage-at-the-ports-of-los-angeles-and-long-beach/. 
  14. ↑ Mongelluzzo, Bill (July 23, 2020). "Chassis equipment issues reemerge at LA–LB port complex". https://www.joc.com/port-news/us-ports/chassis-equipment-issues-reemerge-la%E2%80%93lb-port-complex_20200723.html. 
Further reading
  • National Academies of Sciences, Engineering, and Medicine. (2011). "Chapter 8: Container Chassis Supply Time and Delays". Truck Drayage Productivity Guide. Washington, DC: National Academies Press. doi:10.17226/14536. ISBN 978-0-309-15552-6. 

External links



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